Imagine a European country where one person can pick the judges. And effectively sack them or transfer them to other courts. And draw up court rules. And initiate legislation on the courts. And hold some 60 other specified legal powers.

Now imagine that this individual has been just given a nine-year term of office. And that, even after that term is up, this hugely powerful figure will simply remain in office unless a successor can command a two-thirds majority in the country's parliament. What would you call a country like that?

The answer, of course, is Hungary. All these powers are in the hands of Tünde Handó, a former judge and president of the newly established national judicial office (NJO). No doubt it's pure coincidence that she is married to József Szájer, a founding member of the ruling Fidesz party and the man credited with drawing up Hungary's constitution on his iPad. Szájer resigned his posts in the domestic party when his wife was appointed in January, but remains a member of the European parliament and a key figure who briefed reporters over breakfast at the Hungarian embassy in London last month.

Little wonder, then, that Hungary was told this week to modify its judicial system. The call came from the Venice commission, the Council of Europe's highly-respected but little-known advisory body on constitutional structures. Its members include senior academics, constitutional lawyers, judges and members of national parliaments. "In no other member state of the Council of Europe are such important powers, including the power to select judges and senior office-holders, vested in one single person," the commission concluded.

Given the "high procedural obstacles in the way of a removal procedure" and the NJO president's "extremely wide competences", the Venice commission insisted that Handó's "accountability must be increased". In particular, "binding decisions should be subject to judicial review".

In contrast to Handó's all-powerful NJO, Hungary also has a national judicial council, elected from among the judges. The Hungarian government told the Venice commission that the judges' council's "main and most important power" was to initiate the removal of the NJO president from office.

But the commission was not impressed. This was no more than a right to put a request to parliament, it concluded. The council's decisions were not binding and its opinions could be ignored. According to the Venice commission, the judges' council "has scarcely any significant powers and its role in the administration of the judiciary can be regarded as negligible".

And that's quite apart from the fact that nearly 10% of the Hungarian judiciary are losing their jobs because the retirement age is being reduced from 70 to 62. "A whole generation of judges, who were doing their jobs without obvious shortcomings and who were entitled - and expected - to continue to work as judges, have to retire," the commission notes. Handó will then be able to promote more than 200 judges to the most senior positions.

Responding to the Venice commission report this week, the Hungarian government promised to introduce legislation that would transfer some of the administrative tasks of the NJC president to the national judicial council and augment the council's existing supervisory powers. In future, the NJC president would only be able to exercise certain powers in accordance with principles prescribed by the judicial council, the ministry of public administration and justice said.

Who asked the Venice commission for their opinion in the first place? The answer is Hungary, whose government invited a delegation to Budapest last month and provided "excellent co-operation". The delegation spoke to Handó, among others. It says, in effect, that she should not take its comments personally.

But it is impossible to ignore the commission's conclusion. Asked to examine Hungarian laws on the independence of the judiciary, the commission says: "the reform, as a whole, threatens the independence of the judiciary."

And the Hungarians can't say they didn't know what to expect. Last June, the Venice commission published a report on Hungary's new constitution, which had been passed two months earlier and came into force at the beginning of this year.

The commission concluded that too many provisions in the constitution had been designated as "cardinal laws", which could not be amended without a two-thirds majority in parliament. Some of these should have been left to ordinary legislation, the commission said. "When not only the fundamental principles but also very specific and detailed rules on certain issues will be enacted in cardinal laws," it added, "the principle of democracy itself is at risk."